I read today. the Indo Australia plate has a fracture running off Sumatra and trending N-South "good for gold apparently" and about 2000 km West of the WA coast. It's a nice straight rift and has been in existence as long as India has. 200 million years ago. or when Pangaea broke up. the indo bit of our plate or actually the bit next to it, is the fastest moving tectonic drift in the world. Mount Everest is gaining 10 cm a year at its summit that's how fast it is. Its off the show in its speed, for a cooling planet.
The fracture is perhaps several hundred thousand years away from making our own tectonic plate a bit smaller and eventually separating and eventually breaking off. But hey. No chance of a caldera.